Nonlinear reduction in risk for colorectal cancer by oral contraceptive use: a meta-analysis of epidemiological studies.

PURPOSE: Although the relationship between oral contraceptive (OC) use and colorectal cancer (CRC) risk has been studied extensively, the results of epidemiological studies are controversial. Therefore, we carried out a meta-analysis of epidemiological studies to summarize the available evidence and to quantify the potential dose-response relation. METHODS: We searched PubMed database for studies of OC use and CRC risk that were published until the end of March 2014. Random- and fixed-effects models were applied to estimate summary relative risks (RRs) and 95 % confidence intervals (CIs). RESULTS: Twelve cohorts and seventeen case-control studies with a total of 15,790 CRC cases were included in the final analysis. The summary RR for the ever versus never category of OC use was 0.82 (95 % CI 0.76-0.88). Similar result was observed when we compared the longest duration of OC use with the shortest duration (RR = 0.86, 95 % CI 0.76-0.96). Furthermore, the results of stratified analysis were comparable to those of overall meta-analysis. In dose-response analysis, significant inverse associations emerged in nonlinear models for the duration of OC use and CRC (P nonlinearity = 0.001). The greatest risk reduction was observed when the duration of OC use was approximately 42 months. There was moderate heterogeneity in the analysis, and no evidence of small-study bias was observed. CONCLUSIONS: Based on the findings of this meta-analysis, ever use of OC is associated with lower risk of CRC. Additionally, there is a statistically significant nonlinear inverse association between the duration of OC use and CRC risk.

Breastfeeding and ovarian cancer risk: a meta-analysis of epidemiologic studies.

BACKGROUND: Epidemiologic studies have yielded inconsistent findings between breastfeeding and epithelial ovarian cancer (EOC) risk. OBJECTIVE: We performed a meta-analysis to summarize available evidence of the association between breastfeeding and breastfeeding duration and EOC risk from published cohort and case-control studies. DESIGN: Relevant published studies were identified by a search of MEDLINE through December 2012. Two authors (T-TG and Q-JW) independently performed the eligibility evaluation and data abstraction. Study-specific RRs from individual studies were pooled by using a random-effects model, and heterogeneity and publication-bias analyses were conducted. RESULTS: Five prospective and 30 case-control studies were included in this analysis. The pooled RR for ever compared with never breastfeeding was 0.76 (95% CI: 0.69, 0.83), with moderate heterogeneity (Q = 69.4, P < 0.001, I(2) = 55.3%). Risk of EOC decreased by 8% for every 5-mo increase in the duration of breastfeeding (RR: 0.92; 95% CI: 0.90, 0.95). The risk reduction was similar for borderline and invasive EOC and was consistent within case-control and cohort studies. CONCLUSIONS: Results of this meta-analysis support the hypothesis that ever breastfeeding and a longer duration of breastfeeding are associated with lower risks of EOC. Additional research is warranted to focus on the association with cancer grade and histologic subtypes of EOC.

[Study of the energy transfer between excited Rb2 and H2 using the CARS technique].

Using the CARS (coherent anti-Stokes Raman spectroscopy) detection technique, the authors investigated the electronic-to-rovibrational levels energy transfer between electronically excited Rb2 and H2. In this CARS experiment, the S-branch (delta upsilon = 1, delta J = 2) transition of H2 was excited by two laser pulses, the pump and the Stokes, respectively, centered at 532 and 690 nm. The internal state distribution of collisionally populated H2 was probed. The scanned CARS spectra reveal that during energy transfer processes H2 molecules were produced only at the upsilon = 1, J = 1,2 and upsilon = 2, J = 0,1,2 rovibrational levels. From scanned CARS spectral peaks the population ratios were obtained. The n1/n5, n2/n5, n3/n5 and n4/n5 are 3.57 +/- 0.71, 2.65 +/- 0.53, 3.00 +/- 0.60 and 0.93 +/- 0.17, respectively, where n1, n2, n3, n4 and n5 represent the number densities of H2 at the rovibrational levels (2,0), (2,1), (2,2), (1,1) and (1,2), respectively. The population ratios indicate that the H2 molecules produced by the energy transfer process are 83% populated at the upsilon = 2 vibrational level and 17% at upsilon = 1. The relative fractions ( : = of average energy disposal were derived as (0.48, 0.01, 0.51), with major translational and vibrational energy release. Through semilog plot of the time-resolved CARS profiles under a simple kinetic model under the experimental conditions of T = 573 K and P = 5 x 10(3) Pa, the collisional transfer rate coefficients k12 = (3.1 +/- 0.6) x 10(-14) cm(-3) x s(-1) and k2 = (4.9 +/- 1.0) x 10(-15) cm(-3) x s(-1) have been obtained.

[Excitation and relaxation of metastable state NaK(1 3Pi) at high vibrational levels].

The authors have investigated collision vibrational energy transfer rate constants in NaK[1 3Pi(v)] and He system. Pump laser excitation of the spin-forbidden band was used to produce very highly vibrationally excited metastable state NaK[1 3Pi (v = 22, 21, 20)]. The probe laser was used to excite the 1 3Pi (v = 22, 21, 20) to 5 3Pi(v'). Laser induced fluorescence (LIF) from 5 3Pi --> 1 3Sigma+ transition was used to follow the collision dynamics. The semilog plots of time-resolved LIF was obtained. The slopes yielded the effective lifetimes. From such data several Stern-Volmer plots could be constructed and the relaxation rate constants could be extracted for the sum of all processes that give rise to the decay of the prepared vibrational state. The rate constants (in units of 10(-11) cm3 x s(-1)) for v being 22, 21 and 20 are 1.4 +/- 0.1, 1.2 +/- 0.1 and 1.0 +/- 0.1, respectively. The vibrational relaxation rate is increasing with vibrational quantum number. In order to determine the importance of multiquantum relaxation, it is necessary to measure the relative population of both the prepared state and collisionally populated states. By the kinetic equations governing up to Delta(v) = 2 transitions, the time dependence of populations of the vibrational states were obtained. With the help of the integrating the population equations over all time, the importance of the two-quantum relaxation could be studied experimentally. By varying the delay between the pump and the probe laser, the He pressure dependent vibrational state specific decay could be measured. The time evolutions and relative intensities of the three states v = 22, 21 and 20 by preparing v = 22 were obtained. Using experimental data the rate constants (in units of 10(-11) cm3 x s(-1)) for v = 22 --> 21 and v = 22 --> 20 are 0.67 +/- 0.15 and 0.49 +/- 0.12, respectively. The single quantum relaxation accounts for only about 48% of the total relaxation out of v = 22. Multi-quantum relaxation (Delta(v) > 1) was found to be important at high vibrational states.

[Correlation between the expression of high mobility group box 1 and receptor for advanced glycation end products and the onset of pre-eclampsia].

OBJECTIVE: To evaluate different expressions of high mobility group box 1 (HMGB1) and receptor for advanced glycation end products (RAGE) in placentas and their relationship with pre-eclampsia. METHODS: Fifteen early-onset pre-eclamptic women (early-onset pre-eclampsia group), 22 late-onset pre-eclamptic women (late-onset pre-eclampsia group) and 12 normotensive women (control group) in the third trimester were recruited at the Shengjing Hospital of China Medical University from March 2006 to March 2007. The localization and levels of HMGB1 and RAGE in placentas of the three groups were detected by the strept avidin biotin-peroxidase method. RESULTS: (1) Immunoreactivities to HMGB1: positive immunostaining for HMGB1 was observed in trophoblast, macrophages, decidual cells, vascular muscle cells, endothelial cells and placental mesenchymal cells in the placentas from the pre-eclamptic women, while a low level of immunoreactivities was observed in the placentas from healthy pregnancies; the staining was observed within both the nuclei and the cytoplasm, mainly in the cytoplasm. The cytotrophoblast, especially the nuclei was extensively positive for HMGB1 in early-onset pre-eclampsia. (2) Immunoreactivities to RAGE: positive immunostaining for HMGB1 was observed in syncytiotrophoblast, macrophages and endothelial cells in the placentas from the preeclamptic women, while a low level of immunoreactivities was observed in the placentas from healthy pregnancies; the staining was in the cytoplasm and (or) cell membrane. The trophoblast was extensively positive for RAGE in early-onset pre-eclampsia. (3) Positive rate of HMGB1 expression: the expression of HMGB1 in early-onset group (73%, 11/15) and late-onset group (64%, 14/22) was significantly higher than that in normal group (17%, 2/12; P < 0.05), but no significant difference was found in early-onset group and late-onset group (P > 0.05). (4) Positive rate of RAGE expression: the expression of RAGE in early-onset group (80%, 12/15) and late-onset group (82%, 18/22) was significantly higher than that in normal group (25%, 3/12; P < 0.05), but no significant difference was found in early-onset group and late-onset group (P > 0.05). CONCLUSIONS: The increased expression of HMGB1 and RAGE in the placenta may play an important role in the pathogenesis of pre-eclampsia. The different locations may be associated with the occurrence of different onset types of pre-eclampsia.

[Clinical significance of hypoxia inducible factor-prolyl hydroxylase 1 and factor inhibiting hypoxia inducible factor-1 expression in placentas of women with severe pre-eclampsia].

OBJECTIVE: To investigate the role of hypoxia inducible factor (HIF)-prolyl hydroxylase 1 (HPH1) and factor inhibiting HIF-1 (FIH-1) in placentas in the pathogenesis and development of severe pre-eclampsia. METHODS: RT-PCR and western blot analyses were used to detect the HPH1 and FIH-1 expression levels in placentas of 34 patients with severe pre-eclampsia and 24 cases of term pregnancy (normal pregnancy group) and their correlations with symptoms were analyzed. RESULTS: (1) The HPH1 mRNA and protein expression levels in placentas of severe pre-eclampsia group were 0.40 +/- 0.04 and 59.5 +/- 3.4 separately, significantly lower than those of normal pregnancy group, 0.84 +/- 0.12 and 71.6 +/- 1.7 (P < 0.01). The FIH-1 mRNA and protein expression levels in placentas of severe pre-eclampsia group were 0.31 +/- 0.05 and 45.6 +/- 2.4 separately, significantly lower than those of normal pregnancy group, 0.43 +/- 0.04 and 54.9 +/- 2.1 (P < 0.01). (2) The mRNA and protein expression levels of HPH1 and FIH-1 in severe pre-eclampsia group were all negatively correlated with mean arterial pressure (MAP) [the Spearman correlation coefficient was -0.854 (P < 0.01)], urinary protein per 24 hours [the Spearman correlation coefficient was -0.936 (P < 0.01)] and the occurrence of fundus oculi artery spasm [the Spearman correlation coefficient was -0.854 (P < 0.01)]. (3) The expression of HPH1 mRNA in placentas of all the 58 cases was 0.58 +/- 0.27, higher than the expression of FIH-1 mRNA, which was 0.39 +/- 0.10. There was a positive correlation between them. The pearson correlation coefficient was 0.686 (P < 0.01). The expression of HPH1 protein in placentas of all the 58 cases was 64.5 +/- 6.7, higher than the expression of FIH-1, which was 49.4 +/- 5.2. There was a positive correlation between them. The Pearson correlation coefficient was 0.947 (P < 0.01). CONCLUSION: The expression imbalance of HPH1 and FIH-1 in placenta may play an important role in the pathogenesis and development of severe pre-eclampsia through inhibiting HIF-1alpha.